The spider genus Ancylometes Bertkau, 1880 is revised. A. vulpes Bertkau, 1880, type species of the genus, is considered a junior subjective synonym of Dolomedes concolor Perty, 1833. Both types are lost and we redescribe the species based on specimens similar to those found at the type locality of A. vulpes. Spiders of the genus are large nocturnal ground-living hunting spiders with a strong affinity in most species, to water bodies within their tropical environment. Those species hunt also on small vertebrates like frogs, tadpoles and fishes. All species show slight sexual dimorphism in colour and body-to-leg-size relations. Females carry brown egg-sacs in chelicerae and build a nursery web. The genus is morphologically diagnosed by the presence of ventral spines on tarsi III and IV in both sexes and by their genital characters: filiform embolus with a basal membranous lobe, wing-like conductor and hammer-like median apophysis in males; female epigyne consisting of two broad lateral plates and a central plate in form of a bike saddle with its nose pointing posteriorly. Ten valid species are recognized and described, five of them are new: Ancylometes japura, A. jau, A. riparius from Amazonas, A. terrenus from Acre, Amazonas and Mato Grosso and A. pantanal from Matto Grosso do Sul, all from Brazil. The female of A. amazonicus is described for the first time and the female of A. hewitsoni for the first time based on an adult specimen. Ancylometes vulpes Bertkau, Ctenus argentinus Holmberg, Ancylometes bolivianus Tullgren, Lycoctenus bahiensis Strand, Lycoctenus selenkae Strand, Lycoctenus paraguayensis Strand, Cupiennius argentinus Petrunkevitch, Ctenus paulensis Mello-Leitão, Cupiennius diplocellatus Mello-Leitão, Ctenus originalis Mello-Leitão, Ctenus iophorus Mello-Leitão, Corinoctenus anomalostomus Mello-Leitão, Ctenus infelix (Mello-Leitão, Ctenus metatarsalis Mello-Leitão, Phoneutria niveobarbata Mello-Leitão and Corinoctenus greenwayi Carcavallo & Martinez are newly synonymized with A. concolor (Perty). Ctenus fuscus Walckenaer, Ctenus giganteus Taczanowski, Ctenus bimaculatus Taczanowski, Leptoctenus tenkatei Hasselt, Lycoctenus brunneus Pickard-Cambridge, Lycoctenus gigas Pickard-Cambridge, Lycoctenus demerarensis Pickard-Cambridge, Lycoctenus saraensis Strand, Lycoctenus paraensis Strand, Ancylometes pindareensis Mello-Leitão, Ancylometes pindareannus Mello-Leitão, Ctenus juruensis Mello-Leitão, Ctenus striolatus Mello-Leitão, Ctenus xerophilus Mello-Leitão and Lycoctenus titanus Caporiacco are newly synonymized with A. rufus (Walckenaer). Lycoctenus palustris Pickard-Cambridge, Ancylometes orinocensis Simon, Lycoctenus venezuelensis Strand, Lycoctenus caracasensis Strand and Ctenus nasutus Kraus are newly synonymized with A. bogotensis (Keyserling). A. valentinei Petrunkevitch, 1925 from Panama is a Cupiennius (new combination) and considered a senior synonym of C. panamensis Lachmuth et al., 1985. The geographical distribution is Neotropical, with one northern widespread species (A. bogotensis) reaching Central America, one widespread species of the Amazon reaching the São Paulo coastal area and one widespread species of central Brazil reaching Argentina. From the Amazon region six rarely collected species are described and one species was recently collected in the Pantanal of Brazil.